Vitamin D (Cholecalciferol)

General Description

The term vitamin D is used to describe two substances from two different
sources. Vitamin D-3, cholecalciferol, is formed from cholesterol and
is synthesized in the body during exposure to ultraviolet light (e.g.
sunlight). The other substance is vitamin D-2, ergocalciferol, which is
found in plants and is used to fortify foods such as margarine, cereals,
and milk. Both substances perform the same function in the body.

Health Applications

Bone health

Aids calcium absorption

Skin health

Functions and Uses

Vitamin D (cholecalciferol and ergocalciferol) promotes intestinal absorption
of calcium and phosphate into the blood stream. It also frees calcium
from bones for use in other parts of the body. It is essential for normal
bone growth and development. It also works in the kidneys to prevent calcium
and phosphate loss through urine. Both forms of vitamin D are converted
by the body into an active form called calcitriol. The liver and kidneys
are involved in this process. For this reason, kidney failure often results
in calcium deficiency symptoms.

Dosage/Toxicity

Vitamin D is available in many multivitamin formulas. The RDI is 400 IU
of vitamin D daily. This recommendation does not take into account the
fact that people may be producing sufficient amounts of the vitamin due
to exposure to the sun. It can be toxic if taken in doses larger than
2,000 IU. Symptoms of toxicity are headache, nausea, vomiting, metal taste
in the mouth, fatigue, and muscle and bone pains. In addition, excess
vitamin D can lead to an accumulation of calcium in vital organs, such
as the liver and kidneys, with potentially dangerous consequences.